A Phase 1, open-label, crossover study evaluating the effect of a single dose of sodium zirconium cyclosilicate on the pharmacokinetics of tacrolimus and cyclosporin

ABSTRACT

Background

Sodium zirconium cyclosilicate (SZC) is an oral, highly selective potassium binder approved for the treatment of hyperkalaemia in adults. SZC may change the absorption of co-administered drugs that exhibit pH-dependent bioavailability. This study evaluated whether the pharmacokinetic (PK) profiles of tacrolimus and cyclosporin were altered by concomitant SZC administration in healthy participants.

Methods

This was an open-label, randomised sequence, two-cohort crossover, single-centre study. Healthy adults were assigned to one of two cohorts: Cohort 1 (tacrolimus) received a single dose of tacrolimus 5 mg and tacrolimus 5 mg + SZC 15 g in a random order; Cohort 2 (cyclosporin) received a single dose of cyclosporin 100 mg and cyclosporin 100 mg + SZC 15 g in a random order. Primary PK endpoints were maximum observed blood concentration (C _max) and area under the concentration–time curve (AUC) from time zero to infinity (AUC _inf). Differences in mean C _max and AUC _inf were analysed using a mixed effects model.

Results

Thirty participants in Cohort 1 and 29 in Cohort 2 completed the study. Tacrolimus exposure was lower with tacrolimus + SZC versus tacrolimus alone: C _max geometric mean ratio (GMR) 71.10% [90% confidence interval (CI) 65.44–77.24], AUC _inf 62.91% (55.64–71.13). Cyclosporin exposure was similar with cyclosporin + SZC compared with cyclosporin alone: C _max GMR 102.9% (90% CI 96.11–110.10), AUC _inf 97.23% (92.93–101.70).

Conclusions

Tacrolimus exposure was lower when co-administered with SZC 15 g and should be administered ≥2 h before or after SZC. The PK profile of cyclosporin was not affected by SZC co-administration.

Graphical Abstract

Graphical Abstract